The present invention relates to cyclodextrin and, more specifically, to the removal of residual cyclodextrin from a system without contaminating the system with enzyme. The present invention is especially applicable to food systems.
In recent years cyclodextrin has been used to remove unwanted substances from a number of different systems, especially food systems. For example, cyclodextrin has been used to remove cholesterol from eggs and butter; caffeine from chocolate, tea and coffee; phenylalanine from protein hydrolysates; and phenolic compounds, pigments and bitter components from fruit juice. Typically, this removal process entails a two-step process of first mixing cyclodextrin or an aqueous slurry of cyclodextrin with the food system to form a complex between the cyclodextrin and the unwanted substance; and subsequently removing the complex from the food system. Conventionally, the complex is then separated into its individual components and the cyclodextrin recycled to be used again in the removal process.
One of the problems associated with this process is that a small amount of cyclodextrin is left in the system after the complex is removed from the system. The source of this residual cyclodextrin is twofold, unrecovered complex and unremoved, uncomplexed cyclodextrin. Since the complexation process is an equilibrium reaction, an excess amount of cyclodextrin is mixed into the system to push the equilibrium toward complexation. This inevitably means that a certain amount of cyclodextrin is in the uncomplexed state when the complex is removed from the system. Some of the uncomplexed cyclodextrin is left behind in the system when the complex is removed from the system, thus accounting for the unremoved, uncomplexed cyclodextrin.
The other source of residual cyclodextrin, unremoved complex, is due to the inefficiency of the removal of the complex from the system. In some food systems, for example coffee, the complex is removed as a precipitate from solution. Oftentimes soluble or readily suspendable complexes are not removed from the system. In other cases, such as butter, the complexes are removed by washing the butter with water. In these instances, not all of the complex is washed away. In either case, washing or precipitation, the unrecovered complex goes through an equilibrium reaction wherein the guest and cyclodextrin move between a complexed and uncomplexed state. Thus, the unremoved complex is another source of residual cyclodextrin. No matter what the source, the residual cyclodextrin must be removed from the system. The term residual cyclodextrin as used in the specification and claims means cyclodextrin which remains in the system after the majority of the complex has been removed from the system.
It has been suggested that the residual cyclodextrin be removed from egg yolk or egg yolk plasma by adding a soluble enzyme to the egg yolk and then incubating the system to allow the enzyme to decompose the cyclodextrin. Specifically, U.S. Pat. No. 4,980,180 teaches using a soluble alpha-amylase derived from the microorganisms of the group Aspergillus niger, Aspergillus oryzae, Bacillus polymyxa, Bacillus coagulans, Flavobacterium, or domestic hog pancreas amylase to remove cyclodextrin from eggs. A problem associated with soluble alpha amylases which have been used to hydrolyze cyclodextrin is that they do not hydrolyze all cyclodextrin. Specifically, it has been found that they do not hydrolyze branched cyclodextrin and they do not hydrolyze all of the alpha cyclodextrin.
It has also been suggested to use a combination of alpha-amylase and cyclodextrin glycosyl transferase (CGTase) to hydrolyze the residual cyclodextrin. Such a combination has been found to hydrolyze virtually all of the residual cyclodextrin.
Whether using one or two enzymes to remove residual cyclodextrin, these enzymes remain in the system and must be inactivated. Typically, the enzymes are inactivated by a conventional means such as high temperature or extremely high or low pH. Such an inactivation step is not acceptable in food systems like milk and eggs because such an inactivation step can change the physical properties of the treated food. Additionally, the inactivated enzyme remains in the system and acts as a contaminant to the system. There is a need for a process wherein residual cyclodextrin is removed from a system without the need to go through a deleterious step to inactivate the enzyme and without contaminating the system with inactivated enzyme.